Spatial variability and environmental drivers of cassava—arbuscular mycorrhiza fungi (AMF) associations across Southern Nigeria

Abstract

Cassava, forming starch-rich, tuberous roots, is an important staple crop in smallholder farming systems in sub-Saharan Africa. Its relatively good tolerance to drought and nutrient-poor soils may be partly attributed to the crop’s association with arbuscular mycorrhiza fungi (AMF). Yet insights into AMF-community composition and richness of cassava, and knowledge of its environmental drivers are still limited. Here, we sampled 60 cassava fields across three major cassava-growing agro-ecological zones in Nigeria and used a DNA meta-barcoding approach to quantify large-scale spatial variation and evaluate the effects of soil characteristics and common agricultural practices on AMF community composition, richness and Shannon diversity. We identified 515 AMF operational taxonomic units (OTUs), dominated by Glomus, with large variation across agro-ecological zones, and with soil pH explaining most of the variation in AMF community composition. High levels of soil available phosphorus reduced OTU richness without affecting Shannon diversity. Long fallow periods (> 5 years) reduced AMF richness compared with short fallows, whereas both zero tillage and tractor tillage reduced AMF diversity compared with hoe tillage. This study reveals that the symbiotic relationship between cassava and AMF is strongly influenced by soil characteristics and agricultural management and that it is possible to adjust cassava cultivation practices to modify AMF diversity and community structure. Graphical abstract

Effects of Tillage and N Applications on the Cassava Rhizosphere Fungal Communities

“…Arbuscular mycorrhizal fungi (AMF) belong to Glomeromycota, which includes Glomeromycetes, and can be affected by soil characteristics and agricultural practices [57]. Previously, AMF has shown positive effects on cassava growth by improving its nutrient uptake and drought-resistant ability [57][58][59][60]. The relative abundance of Glomeromycota was found to decrease after fertilization [61], and a similar trend can be found in the CT group in 2020 in the current study (Figure 3b).…”

“…Arbuscular mycorrhizal fungi (AMF) belong to Glomeromycota, which includes Glomeromycetes, and can be affected by soil characteristics and agricultural practices [57]. Previously, AMF has shown positive effects on cassava growth by improving its nutrient uptake and drought-resistant ability [57][58][59][60].…”

Diversity of Arbuscular Mycorrhizal Fungi of Kalappia celebica: An endemic and endangered plant species in Sulawesi, Indonesia

“…Chaudhary et al (2018) identified the same biotic and abiotic factors driving AMF species composition in tropical and temperate regions. Several factors have been identified that may influence AMF distributions, including abiotic (e.g., soil physicochemical properties, latitude, climate) (Melo et al 2019;Zhu et al 2020) and biotic (e.g., host plant) factors (Songachan and Kayang 2012;Thanni et al 2022), and intrinsic properties of species (e.g., dispersal ability). Organic C, total N and pH affect the diversity of AMF species (Luo et al 2020).…”

Richness of Arbuscular Mycorrhizal Fungi Under Different Agroforestry Practices in the Drylands of Southern Ethiopia

“…Similarly, [101] did not found significant differences in total fungal diversity between primary forest and palm plantation farm. Similarly, tractor tillage operations increased AMF Shannon diversity while zero tillage decreased Shannon diversity [102]. Moreover, some studies also indicated that high intensity of land use did not change or even increased AMF diversity or species richness [73].…”